i'm using instagram. he's going to look at your picture and see if he can find it based on the data in the photograph. in an instant, hong finds us at 19th and m street. all right, this is our guy. >> are you serious? >> reporter: it's not magic, if you've turned on instagram's location setting, data collected with a photo can actually display your location on a map. you want to explain to david what you did? >> i was looking at the photos and they have the location on there. >> reporter: it's all made possible in a new reality of smartphones and the way they track you using your applications, photos, and games. you looked at some of the most popular smartphone applications? >> that's right, so we looked at the top 100 apps and turns out half had privacy concerns and they are collecting or using sensitive information. this is a really fun game, you know, lots of kids and lots of adults love this. >> reporter: hong and his colleagues reverse engineered the code from the popular game angry birds. >> this is